Final answer:
Louis Pasteur's discovery that bacteria cause diseases is true, as his work laid the foundations for germ theory and led to advances in hygiene, pasteurization, and vaccinations.
Step-by-step explanation:
The statement that Louis Pasteur discovered that bacteria actually cause diseases is true. Pasteur was a pioneering French chemist who, through his experiments on fermentation, demonstrated the role of microorganisms in causing diseases. He discovered the process of microbial fermentation in 1856 while studying the causes of spoilage in beer and wine, which led him to suggest that if microbes were responsible for food spoilage and fermentation, they might also be responsible for causing infections. This played a key role in the development of the germ theory of disease, which he supported through further investigation, such as the identification of Streptococcus pyogenes as the cause of puerperal fever.
Additionally, Pasteur's work in microbiology included developing the technique of pasteurization and creating vaccines against diseases like anthrax and rabies, transforming the understanding of health and contributing to a dramatic decrease in deaths from infectious diseases in Europe towards the end of the 19th century.